Arc tube centering device

ABSTRACT

An improved mounting structure for a gas discharge lamp employing a ceramic arc tube mounted on a support frame within an outer glass envelope. The arc tube is secured at one end to a lead in conductor and at its other end is connected to the supporting frame in a manner which substantially restricts all lateral movement of the arc tube with respect to the support frame while permitting free axial movement of one end of the arc tube with respect to the support frame.

United States Patent [72] lnventors Leo C. Werner Cedar Grove;

Raymond M. Kane, Florham Park, both of 2,1 73 26] ArtorneysA. T.Stratton, W. D. Palmer and B. R. Studebaker ABSTRACT: An improvedmounting structure for a gas Pittsburgh, Pa.

discharge lamp employing a ceramic arc tube mounted on a support framewithin an outer glass envelope. The are tube is secured at one end to alead in conductor and at its other end [54] ARC TUBE CENTERING DEVICE 8Claims, 4 Drawing Figs. is connected to the supporting frame in a mannerwhich substantially restricts all lateral movement of the arc tube withrespect to the support frame while permitting free axial movement of oneend of the arc tube with respect to the support e m a c 44 0 u ou u ,2,4 MU m 0U "3N L T C G o s Pm U he. 1 ll 2 0 5 55 l [l ARC TUBE CENTERINGDEVICE BACKGROUND OF THE INVENTION This invention relates to highpressure gas discharge lamps and more particularly to an improvedmounting structure for a ceramic discharge lamp.

In the past, ceramic discharge lamps have been mounted in acomparatively rigid relationship with respect to the support frame. Anexample of such a mounting may be found in US. Pat. No. 3,384,798 issuedMay 21, I968 to K. Schmidt. Such rigid mounting generally accomplishedby welding the arc tube to a strap which served both as a support and alead in conductor provided for good lateral support and desirablymaintained the arc tube in a central position within the outer envelope.This type structure, however, also provided for rigid axial support ofthe arc tube and does not accommodate vertical expansion of the arc tubeduring operation of the lamp.

It has been found that it is highly desirable when mounting a ceramicarc tube within an outer envelope in a ceramic discharge lamp that thearc tube be maintained in a central location with respect to the outerenvelope by means of a comparatively rigid mounting structure in orderthat the arc tube is not jarred, during shipment or upon other impact,to an extent that the arc tube will shift to a position other than itsoriginal central location within the outer envelope. It has, however,also been found that it is equally desirable to provide axialflexibility in the arc tube mount in order to allow for verticalexpansion of the arc tube during operation of the lamp.

SUMMARY OF THE INVENTION The above-described deficiencies in the priorart structures are obviated and the improvements are accomplished inaccordance with the present invention by providing, in a gas dischargelamp having a base portion, an envelope portion sealed thereto andenclosing a reentrant stem press having a pair of lead in conductorsextending therethrough onto which is mounted an arc tube mounting andsupport frame and an arc tube; the improvement which comprises means forconnecting the arc tube to the frame, which connecting means,substantially restricts all lateral movement of the arc tube withrespect to the support frame but permits substantially free axialmovement of one end of the arc tube with respect to the support frame.

BRIEF DESCRIPTION OF THE DRAWING Many of the attendant advantages of thepresent invention will become more readily apparent and betterunderstood as the following detailed description of exemplaryembodiments is considered in connection with the accompanying drawingsin which: 7

FIG. I is a side elevation view partly in section of an arc dischargelamp constructed in accordance with the present invention;

FIG. 2 is a fragmentary sectional view taken along the line Il-II ofFIG.1;

FIG. 3 is a view similar to FIG. I of the upper portion of the arc tubemount illustrating an alternative embodiment of the present invention;and

FIG. 4 is a view similar to FIG. 3 illustrating yet another embodimentof the arc tube support ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to thedrawings wherein like reference characters represent like partsthroughout the several views there is illustrated in FIG. 1 oneembodiment of the arc tube mounting structure of this invention. Theceramic discharge lamp generally designated includes an outer envelopeof glass 12 attached to a standard mogul base 14. A pair of lead inconductors 16 and 18 are conventionally connected to the mogul base 14and extend through a reentrant stem press 20 at the base of the envelope12in a conventional manner. Mounted on the upper end of lead inconductor 18 is the arc tube support frame 22 which serves both toretain and mount the arc tube within the outer envelope as well as toconduct electricity to the upper electrode of the arc tube. The frame 22is supported at its upper end within the envelope 12 by a pair ofresilient spring members 24 which serve to retain the frame 22 in acentral location within the outer envelope 12 through resilient contactwith the inner surface of the outer envelope.

A conventional ceramic arc tube 26 is mounted at its lower end to leadin conductor 16 by means of a strap 28 which is welded at one end to thelead in conductor 16 and at its other end to the pinched off end of theexhaust and fill tabulation 30 of the arc tube which, in its pinched offform. serves as a lead in conductor to its associated electrode.

In the embodiment of FIGS. 1 and 2 the upper end of the arc tube 26 issecured to the cross member 32 of the support frame 22 by means of adouble leaf, spring clip 34. As best seen in FIG. 2 the resilient doubleleaf spring clip has a top portion 36 that surrounds and is welded tothe top member 32 of the support frame 22 and extends downwardly in apair of legs which are secured together as by welding at 37. Each legthen extends outwardly in a U-shaped configuration 38 and then back to aparallel leg configuration at 39 where both legs are again weldedtogether and to an upper lead in conductor 40 connected to the upperelectrode of the ceramic arc tube. The bottom leg portions 39 terminatein feet portions 39a which serve to aid in retaining the arc tube in itscentral location. In the embodiment of FIG. I the flexible U-shapedportions 38 of the legs permit'axial expansion of the arc tube 26 butretain the arc tube'in a rigid position along the center line of theouter envelope 12. The flexible spring clip 34 also serves to conductelectricity from the upper cross member 32 of the support member 22 tothe lead in conductor 40 at the upper end of the ceramic are tube.

In the'embodiment of FIG. 3 an elongated eyelet 42 with a central bore44 is welded to the upper end of the arc tube 26. A current conductingstrap 46 electrically connects the eyelet 42 to the support frame 22through which electricity is carried to the upper electrode of the arctube. A pin or rod 48 is welded to the upper cross bar member 32 ofsupport frame 22 in a position which permits it to extend downwardlyfrom the cross bar member 32 substantially axially of the outer envelopel2 and is slidably received by the central bore 44 in the eyelet 42. Aswill be apparent this construction while maintaining the 'arc tuberigidly in a central position with respect to the outer envelope and thesupport frame 22 will permit axial expansion of the arc tube withoutrestraint during operation of the lamp.

The embodiment of FIG. 4 is quite similar to the FIG. 3 embodiment withthe exception that the pin and aperture relationships are reversed. Inthe FIG. 4 embodiment an elongated pin or rod 50 extends from the upperend enclosure member of the arc tube 26 in electrical contact therewith.A flexible electrically conductive strap 46 is welded to the pin 50 andto the support frame 22 to provide for the conduction of electricity tothe upper electrode of the arc tube. A rigid bar 52 is welded to theupstanding current carrying legs of the frame 22 parallel with the uppercross bar member 32 but spaced a slight distance therefrom. The rigidcross piece 52 has an aperture 54 therein through which the pin 50extends. The coaction between the aperture 54 and the pin 50 retains thearc tube in a preselected position axially of the lamp envelope 12 butplaces no restraint on the axial expansion of the arc tube duringoperation of the lamp.

As will be apparent from the foregoing, each of the above describedembodiments of this invention serve to mount the ceramic arc tube withinan outer envelope in a manner which substantially restrains all lateralmovement of the arc tube with respect to the support frame and the outerenvelope of the lamp and which will retain the arc tube in an axialposition unaffected by any impact during shipment or handling but willpermit substantially free axial movement of the arc tube with respect tothe frame to thereby accommodate expansion of the arc tube duringoperation of the lamp.

What is claimed is:

1. In a gas discharge lamp having a base portion, a sealed bulb portionconnected thereto and a pair of lamp lead in conductors extending fromsaid base portion into said bulb portion onto which are mounted an arctube mounting frame and are tube, the improvement comprising:

mounting means connecting said arc tube to said frame, said mountingmeans including a resilient spring clip welded at one end to said frameand at the other end to said are tube, said resilient spring clipincluding a bowed horizontally disposed section adapted to substantiallyrestrict all lateral movement of said are tube with respect to saidframe but permitting substantially free axial movement of said are tubewith respect to one end of said frame to thereby accommodate expansionof said are tube during operation of said lamp.

2. In a gas discharge lamp having a base portion, a sealed bulb portionconnected thereto and a pair of lamp lead in conductors extending fromsaid base portion into said bulb portion onto which are mounted an arctube mounting frame and are tube, the improvement comprising:

mounting means connecting one end of said are tube to said frame, saidmounting means including an elongated axially disposed pin and a memberhaving an aperture therein; one of said pin and said member being fixedto said arc tube mounting frame and the other of said pin and saidmember being fixed to said one end of said are tube, said pin and saidmember providing the sole support for said one end of said are tube whensaid pin is received in said aperture in said member to therebysubstantially restrict all lateral movement of said are tube withrespect to said frame but permit substantially free axial movement ofsaid are tube with respect to one end of said frame to therebyaccommodate expansion of said are tube during operation of said lamp. 3.In a gas discharge lamp having a base portion, a sealed bulb portionconnected thereto and a pair of lamp lead in conductors extending fromsaid base portion into said bulb portion onto which are mounted an arctube mounting frame and are tube, the improvement comprising:

mounting means connecting one end of said are tube to said frame, saidmounting means including an elongated axially disposed pin welded tosaid frame and an eyelet attached to the end of said are tube having anaperture therein, said pin being received in said aperture in saideyelet to thereby substantially restrict all lateral movement of saidarc tube with respect to said frame but permit substantially freeaxially movement of said are tube with respect to one end of said frameto thereby accommodate expansion of said are tube during operation ofsaid lamp.

4. A gas discharge lamp according to claim 2 wherein said pin is axiallyconnected to said are tube and said aperture is located in a transversemember secured to said frame.

5. A gas discharge lamp comprising in combination a base, an outer bulbsealed to said base and a reentrant stem press extending into said bulbfrom said base and having a pair of lamp lead in conductors extendingtherethrough;

an arc tube supporting frame mounted within said outer bulb on one ofsaid lamp lead in conductors;

an arc tube electrically connected at one end directly to the other ofsaid lamp lead in conductors; and

means electrically connecting the other end of said are tube to saidframe, said means including a resilient spring clip connected at one endto said supporting frame and at the other end to said are tube, saidresilient spring clip having a pair of bowed leg portions adapted toaccommodate without significant restraint axial expansion of said aretube whereby said are tube will be free to expand axially while beingretained in a position substantially centrally located with respect tosaid outer bulb.

6. A gas discharge lamp comprising in combination, a base, an outer bulbsealed to said base and a reentrant stem press extending into said bulbfrom said base and having a pair of lamp lead in conductors extendingtherethrough; I

an arc tube supporting frame mounted within said outer bulb on one ofsaid lamp lead in conductors;

an arc tube electrically connected at one end directly to the other ofsaid lamp lead in conductors; and

mounting means connecting the other end of said are tube to said frame,said mounting means including a centrally disposed axially positionedpin member and a member having an axially disposed aperture, one of saidpin member and said member connected to said are tube and the other ofsaid pin member and said member connected to said frame whereby said pinmember extends through said aperture and is free to move therein andthereby provide the sole support for said other end of said are tube andpermit said are tube to be free to expand axially while being retainedin a position substantially centrally located with respect to said outerbulb.

7. A gas discharge lamp comprising in combination, a base, an outer bulbsealed to said base and a reentrant stem press extending into said bulbfrom said base and having a pair of lamp lead in conductors extendingtherethrough;

an arc tube supporting frame mounted within said outer bulb on one ofsaid lead in conductors;

an arc tube electrically connected at one end directly to the other ofsaid lamp lead in conductors; and

mounting means connecting the other end of said arc tube to said frame,said mounting means including a centrally disposed axially positionedpin member welded to said frame and an eyelet having an axially disposedaperture therein attached to the end of said are tube, said pin memberextending through said aperture and free to move therein to therebypermit said are tube to be free to expand axially while being retainedin position substantially centrally located with respect to said outerbulb.

8. A gas discharge lamp according to claim 6 wherein said pin member isaxially connected to said are tube and said aperture is located in atransverse member secured to said frame.

1. In a gas discharge lamp having a base portion, a sealed bulb portionconnected thereto and a pair of lamp lead in conductors extending fromsaid base portion into said bulb portion onto which are mounted an arctube mounting frame and arc tube, the improvement comprising: mountingmeans connecting said arc tube to said frame, said mounting meansincluding a resilient spring clip welded at one end to said frame and atthe other end to said arc tube, said resilient spring clip including abowed horizontally disposed section adapted to substantially restrictall lateral movement of said arc tube with respect to said frame butpermitting substantially free axial movement of said arc tube withrespect to one end of said frame to thereby accommodate expansion ofsaid arc tube during operation of said lamp.
 2. In a gas discharge lamphaving a base portion, a sealed bulb portion connected thereto and apair of lamp lead in conductors extending from said base portion intosaid bulb portion onto which are mounted an arc tube mounting frame andarc tube, the improvement comprising: mounting means connecting one endof said arc tube to said frame, said mounting means including anelongated axially disposed pin and a member having an aperture therein;one of said pin and said member being fixed to said arc tube mountingframe and the other of said pin and said member being fixed to said oneend of said arc tube, said pin and said member providing the solesupport for said one end of said arc tube when said pin is received insaid aperture in said member to thereby substantially restrict alllateral movement of said arc tube with respect to said frame but permitsubstantially free axial movement of said arc tube with respect to oneend of said frame to thereby accommodate expansion of said arc tubeduring operation of said lamp.
 3. In a gas discharge lamp having a baseportion, a sealed bulb portion connected thereto and a pair of lamp leadin conductors extending from said base portion into said bulb portiononto which are mounted an arc tube mounting frame and arc tube, theimprovement comprising: mounting means connecting one end of said arctube to said frame, said mounting means including an elongated axiallydisposed pin welded to said frame and an eyelet attached to the end ofsaid arc tube having an aperture therein, said pin being received insaid aperture in said eyelet to thereby substantially restrict alllateral movement of said arc tube with respect to said frame but permitsubstantially free axially movement of said arc tube with respect to oneend of said frame to thereby accommodate expansion of said arc tubeduring operation of said lamp.
 4. A gas discharge lamp according toclaim 2 wherein said pin is axially connected to said arc tube and saidaperture is located in a transverse member secured to said frame.
 5. Agas discharge lamp comprising in combination a base, an outer bulbsealed to said base and a reentrant stem press extending into said bulbfrom said base and having a pair of lamp lead in conductors extendingtherethrough; an arc tube supporting frame mounted within said outerbulb on one of said lamp lead in conductors; an arc tube electricallyconnected at one end directly to the other of said lamp lead inconductors; and means electrically connecting the other end of said arctube to said frame, said means including a resilient spring clipconnected at one end to said supporting frame and at the other end tosaid arc tube, said resilient spring clip having a pair of bowed legportions adapted to accommodate without significant restraint axialexpansion of said arc tube whereby said arc tube will be free to expandaxially while being retained in a position substantially centrallylocated with respect to said outer bulb.
 6. A gas discharge lampcomprising in combination, a base, an outer bulb sealed to said base anda reentrant stem press extending into said bulb from said base andhaving a pair of lamp lead in conductors extending therethrough; an arctube supporting frame mounted within said outer bulb on one of said lamplead in conductors; an arc tube electrically connected at one enddirectly to the other of said lamp lead in conductors; and mountingmeans connecting the other end of said arc tube to said frame, saidmounting means including a centrally disposed axially positioned pinmember and a member having an axially disposed aperture, one of said pinmember and said member connected to said arc tube and the other of saidpin member and said member connected to said frame whereby said pinmember extends through said aperture and is free to move therein andthereby provide the sole support for said other end of said arc tube andpermit said arc tube to be free to expand axially while being retainedin a position substantially centrally located with respect to said outerbulb.
 7. A gas discharge lamp comprising in combination, a base, anouter bulb sealed to said base and a reentrant stem press extending intosaid bulb from said base and having a pair of lamp lead in conductorsextending therethrough; an arc tube supporting frame mounted within saidouter bulb on one of said lead in conductors; an arc tube electricallyconnected at one end directly to the other of said lamp lead inconductors; and mounting means connecting the other end of said arc tubeto said frame, said mounting means including a centrally disposedaxially positioned pin member welded to said frame and an eyelet havingan axially disposed aperture therein attached to the end of said arctube, said pin member extending through said aperture and free to movetherein to thereby permit said arc tube to be free to expand axiallywhile being retained in position substantially centrally located withrespect to said outer bulb.
 8. A gas discharge lamp according to claim 6wherein said pin member is axially connected to said arc tube and saidaperture is located in a transverse member secured to said frame.